I. The Biology of Matching
Mammals have evolved efficient ways to find and select among potential mates. There has been a great deal of research on this subject in the twenty-three years since a landmark study found that mice choose their mates on the basis of their candidates' distinctive odors. Boyse, E. A.; Beauchamp, G. K.; Yamazaki, K; et al., “Chemosensory Communication—A New Aspect of the Major Histocompatibility Complex and Other Genes in the Mouse.” Journal: Oncodevelopmental Biology and Medicine. Vol. 4 No. 1-2: Pages 101-116, 1982. These odors are defined by the Major Histocompatibility Complex (MHC). The MHC is a cluster of genes that determines details of cellular surfaces and thus immune responses, and specifies certain peptides that appear in skin secretions and urine. These peptides are responsible for odors which uniquely identify individuals who are not identical twins.
More recent work has shown that human female sexual responsivity to a male partner varies linearly and inversely with the degree to which genes in the Major Histocompatibility Complex are shared. Garver-Apgar, Christine E. et al., “MHC Alleles, Sexual Responsivity, and Unfaithfulness in Romantic Couples,” Psychological Science, Volume 17, Number 10, (October 2006). The correspondence is dramatic: about a nine (on a self-reported scale of one to ten) in responsivity to men who share none of a woman's MHC genes and to those who share sixty percent.
Men and women detect others' MHC genes through their body odors. There are a number of peptides that are derived from particular regions of the MHC. These peptides are detected as odors. They strongly affect a woman's responsivity to a particular partner, as discussed in the cited literature, and to both men's and women's mutual attractiveness.
This mate-selection process has a strong effect on the fitness of offspring. Choosing mates on the basis of MHC dissimilarity equips offspring with a broad immune system, increasing the offspring's fitness, and also reduces the rate of spontaneous abortion. It also selects against close relatives as mates, increasing the viability of fetuses and reducing birth defects. It also reduces the rate of spontaneous abortion: there is compelling evidence that fetuses of couples which share significant numbers of MHC alleles are more likely to be rejected in utero. Komlos, L., Zamir, R., Joshua, H., and Halbrecht, I., “Common HLA Antigens in Couples with Repeated Abortions,” Clinical Immunology and Immunopathology 7, Pages 330-335 (1977).
Other studies, including one cited above, have shown that women who are in long-term intimate relationships with men with similar MHC alleles are more likely to report being attracted to and fantasizing about other partners during the fertile portion of their menstrual cycles. This practice obviously has a destabilizing effect on these relationships, which include marriages. Because humans' sense of smell is relatively poor, couples who are strangers must come into close personal contact before they can estimate their MHC-derived “fit” with a potential male partner and thus a woman's long-term sexual responsivity to her partner. As humans have moved from villages to cities, various means have been created to bring men and women of marriageable age into close proximity under controlled conditions: examples range from the masked ball in Romeo and Juliet to modern on-line dating services. In modern human society, with much less class structure and much more freedom for men and women than in tribal, medieval or Victorian eras, and a much higher probability of encountering strangers than in primitive (pre-tribal) eras, this acquaintance process can pose considerable danger and risk of embarrassment to women. The modern process of selecting a mate is very inefficient compared to these earlier societies, in which the number of potential partners available to each woman was comparatively small, and in primitive societies where people lived in very close proximity. It would be of great benefit, not only to individual couples, but to society as a whole, if men and women could assess their sexual compatibility and the health of any offspring of the union without coming into close contact. This would, among other things, give women a wider range of prequalified candidates and would give men greater assurance that they and their prospective mates would have a stable and persistent relationship characterized by mutual physical attraction. It is generally conceded that mutual sexual attraction and responsivity are major contributors to pair bonding: they are the glue that holds long-term relationships together. People of all political and religious persuasions agree that stable pair-bonding, carrying the benefit of reduced strife and relationship discord, is in the best interest of society. Strife and relationship discord result in failed marriages and in infidelity. Society as a whole will thus benefit from easier and more accurate responsivity assessment. It is also important to note that there remain many cultures in which arranged marriages are the norm, and in which affianced couples do not meet before their wedding ceremony. Parents and matchmakers who are concerned with the success of their efforts could gain confidence from an MHC-based genetic matching process before a commitment is made.
Technology has advanced to the point that individual MHC-derived peptides, and thus odors, can be accurately detected artificially using gas chromatography and/or mass spectrometry (an “e-nose”). Willse, Alan et al., “Identification of Major Histocompatibility Complex-Regulated Body Odorants by Statistical Analysis of a Comparative Gas Chromatography/Mass Spectrometry Experiment,” Analytical Chemistry, Vol. 77, No. 8 (Apr. 15, 2005). This implies that a personal odor profile can be constructed for each individual, and that the degree of MHC-allele sharing of two individuals can be derived by comparing those measurements, even if they are strangers and geographically distant from one another. MHC analysis can also be done on the basis of other material, such as cheek-cell scrapings, saliva tests, and other means used in forensic settings.
This process represents a considerable improvement to acquaintance-facilitation (“dating”) services based on the use of questionnaires and personality profiling. While these services help people find partners based on their subjective preferences and personality match, they say little about the likelihood of sexual attraction on first meeting, or the sexual responsivity of the partners in a long-term relationship. In contrast to these methods, MHC comparison is a completely objective process. Unlike current processes which rely on self-administered questionnaires, remote psychological assessments and other user-supplied personal data, MHC comparison cannot misrepresent its user.
II. The Current Market for Matching Services & the Need for Improvement
According to Jupiter Research, online personals revenues will have risen from about four hundred million dollars in 2003, to over six hundred million dollars in 2009. In the United States alone, over seventeen million persons participate in online dating each year (Nielsen Media Research). In 2008, revenue from online dating services will exceed revenue from dating services and personal ads which appear in conventional media (Marketdata Enterprises, Inc.).
Despite this dramatic growth in the online dating industry, many individuals who have used online dating services remain disappointed with their results. The development of a system that provides a tool for predicting good matches based upon applied biological and genetic mechanisms of attraction would fulfill a long felt need in the dating and relationship industry, and would constitute a great benefit to members of society.